Arc-lamp for moving-picture studios.



W. BACH & W. A. CUNNINGHAM.

ARC LAMP FOB MOVING PICTURE STUDIOS.

APPLICATION FILED MAY 16. l9l6.

Patented Mar. 5, 1918.

cu I, R I 8 L m y H T N n M H h 0 w N n U Q A m we H H my 8 WITNESSES W. BACH & W. A. CUNNINGHAM. ARC LAMPFOR MOVING PICTURE STUDIOS.

APPLICATION FILED MAY I6. i916.

//V I/E N TORJ' WiBaci 3?: BY

Patented Mar. 5, 1918.

2 SHEETSSHEET Z ninyain ATTORNEYS WITNESSES kWh for insurin UNITED STATES PATENT OFFICE.

WILLIAM BACK AND WILLIAM ARTHUR CUNNINGHAM, OF NEW YORK, N. Y.

ABC-LAMP FOR MOVING-IBIGTURE STUDIOS.

Specification of Letters Patent.

Patented Mar. 5, 1918.

Application filed May 16, 1916. Serial No. 97,847.

To all whom it may concern:

Be it known that we, WILLIAM. BAGH and WILLIAM A. CUNNINGHAM, citizens of the United States, and residents, respectively, of the city of New York, borough of Manhattan, in the county and State of New York, and New York city, borough of the Bronx, in the county of the Bronx and State of New York, have invented a new and Improved Arc-Lamp for Moving-Picture Studios, of which the following is a full, clear, and exact description.

This invention relates to are lamps especially designed for use in moving picture studios.

The invention has for its general objects to improve the construction and operation of apparatus of this character so as to be reliable and efiicient in use, of extraordinary efliciency compared with other moving picture studio lamps, and so designed as to produce a substantially uniform distribution of light over a wide area.

A more specific object of the invention is the provision of a lamp composed of one or more units, wherein each unit embodies a novel arrangement of carbons or electrodes the best distribution of light from a sing e point.

Another specific object of the invention is to provide a simple, novel and eifective feeding mechanism so designed as to insure a steady arc, this being an important desideratum in moving picture work, because of the great expense involved in making films,v

Fig. 2 is a sectlonal view on the line 2-2, Fig. 1;

Fig. 3 is a perspective view of a lamp composed of a plurality of units; and

Fig. 4 is a detail view of one of the clutches of the carbon feeder.

The lamp may be made of one or more units, according to the maximum amount of light required, and the units may be so controlled that one or more may be used at a time. -When the lamp is made of a plurality of units they are disposed side by side, as in Fig. 3, wherein the units are designated A and A. Each unit comprises a frame of any designed construction, but in the present instance it is formed with horizontal bars 1 and 2 and oppositely sloping side bars 3, whereby the frame tapers downwardly. The top bar 1 is provided with a hanger 4, and through these hangers extends a uniting bar 5, as shown in Fig. 3, whereby the units are fastened together in close relation. Fastened to the bottom of the frame of the unit are lates 6 disposed at an angle of about fortyve degrees to the vertical and meetin at the bottom. These plates are preferab y made of asbestos to resist the heat, and they also serve as reflectors for reflecting downwardly and outwardly the rays of light. Under each plate 6 are carbon or other electrodes 7 and 8, and any number of sets of electrodes may be arranged in each unit. The lower electrodes 7 are removably fastened in brackets 9 carried by the lower ends of the plates 6, and the upper electrodes 8 are fastened in a slide or carrier 10 which moves on theside bars 3, there bein a pair of such bars at each side to provi e a substantial support for the carrier 10. The electrodes 7 and 8 are held in alinement and disposed at an angle of about forty-five degrees to the vertical. One set of electrodes bein to the right and the other to the left of t e vertical center plane of the unit, and consequently light is thrown downwardly and laterally to illuminate a wide area, and as the downwardly directed rays from both arcs meet there is no possibility of a shadow being under the lamp, as is common with lamps heretofore proposed. To insure long burning of the electrodes the same are inclosed in a chamber 12 which is of V-shaped form, as clearly shown in Fig. 1. The plates 6 form the reentrant top of the chamber and the side walls 13 are opaque, as are the walls 14. The chamber has a V-shaped bottom formed by plates of glass 15 which slide upwardly to open position to permit access to the inclosing chamber for trimming the lamp. The walls 14 have apertures 16 in each of which is a porcelain bushin 17 which slidably supports the upper car In.

Connected with each slide 10 is a rod 17 which extends downwardly parallel with the bars 3, and this rod has a series of ratchet teeth 18 with which cooperates a spring lifting pawl 19 carried by a member 20 through which the rod 17 extends. The member 20 is fastened to a tubular core 21 which is guided on a rod 22 extendin through the bore of the core, and fastene to a bracket 23 secured to the bars 3. The core 21 extends into a solenoid 24 which is fastened by a bracket 25 to the bars 3. A spring 26 is connected with the member 20 to exert a pull thereon in a direction to hold the core normally out of the solenoid, and when a solenoid is energized the core moves upwardly and carries with it the member 20, which in turn causes the pawl 19 to grip the ratchet bar 17 and raise the same, which obviously moves the upper carbon away from the lower carbon, so that the illuminating arc is sprung between the carbons.

The solenoid of the feeding device for each set of carbons is connected in series therewith, so that the solenoid will maintain the are at the proper distance. In the arrangement shown in Fig. 1 the lower one of the right set of carbons is connected with a positive supply wire 27 which connects with the bracket 9, andthe current flows upwardly through the right carbons, through the wire 28 connected with the upper carbon, solenoid 24:, wire 29, resistance elements 30, wire 31, solenoid 24 at the left, wire 32, carbons 8 and 7 of the left set, bracket 9 and circuit wire 33. The two sets of carbons are thus in series but it is obvious that they can be connected in parallel.

To insure proper regulation of the feed and steadiness of the arc the solenoids are cooled by a cooling system which embodies a fan 34 mounted on the frame of one of the units, and this fan, which is driven by an electric motor 35, has its outlet 36 connected with an arrangement of distributing pipes 37, and these pipes have connections 38 which lead into the upper ends of the bores of the solenoids 24:, whereby air is directed downwardly through the coils to thereby maintain them at a low temperature. This counteracts the heating of the coil by radiation from the arcs and also by the flow of current. The cores 21 are of smaller diameter than the bores of the solenoids, so that the air can readily flow through the Solenoids, and also so that there is no frictional resistance to the sliding of the cores. The fan may have a horn-shaped inlet 39, as shown by dotted lines in Fig. 3, whereby relatively cool air can be sucked into the fan.

In actual practice, a lamp constructed as shown and operated as described proves to be extremely satisfactory for moving picture work, as it produces a strong, steady light of substantially uniform intensity over a wide area and at a minimum expenditure of power, the cooling of the coils insuring a non-flickering arc. The feed of the carbons takes place instantaneously, so that there is no objectionable interruption in light and a corresponding injury to the film or gap in the scene being photographed. The buming of the carbons at forty-five degrees to the vertical enables a wide distribution of the light, and although the carbons are placed at this angle, they are kept in absolute alinement, so that the tips of the electrodes burn evenly or on centers, and with a steady are.

From the foregoing description taken in connection with the accompanying drawings, the advantages of the construction and method of operation will be readily understood by those skilled in the art to which the invention appertains, and while we have described the principle of operation, together with the apparatus which we now consider to be the best embodiment thereof, we desire to have it understood that the apparatus shown is merely illustrative and that such changes may be made when desired as fall within the scope of the appended claims.

Having thus described our invention we claim as new and desire to secure by Letters Patent:

1. A lamp of the class described comprising a supporting structure, two sets of electrodes arranged on the structure approximately ninety degrees to each other and approximately forty-five degrees to the vertical, means on the structure and positioned above the electrodes for regulating the same,

and plates on the structure and interposed between the electrodes and the said means.

2. A lamp of the class described comprising a supporting structure, two sets of electrodes arranged on the structure approximately ninety degrees to each other and approximately forty-five degrees to the vertical, means on the structure and positioned above the electrodes for regulating the same, plates on the structure and interposed between the electrodes and the said means, and a housing for the electrodes.

3. A lamp of the class described comprising a pair of plates of heat insulating material set at an angle of ninety degrees to each other and forty-five degrees to the vertical, electrode-holding brackets on the plates adjacent the lower meeting ends thereof, and

upper electrodes supported in alinement with the lower electrodes and meeting the latter at points under the plates.

4. A lamp of the class described comprising a pair of plates of heat insulating material set at an angle of ninety degrees to each other and forty-five degrees to the vertical, electrode-holding brackets on the plates adjacent the lower meeting ends thereof, upper electrodes supported in aline- 10 ment with the lower electrodes and meeting the latter at points under the lates, and a housing cooperating with the p. ates to form an inclosing chamber for the electrodes, the

bottom of the chamber being transparent for 15 the distribution of light.

WILLIAM BACK. WILLIAM ARTHUR CUNNINGHAM- 

